Organic 3 Flashcards
What functional group do alcohols contain?
-OH
Word equation for the combustion of ethanol
Ethanol + oxygen -> carbon dioxide + water
Symbol equation for combustion of ethanol
C2H5OH + 3O2 -> 2CO2 + 3H2O
Three ways ethanol can be oxidised:
- burning in air or oxygen (complete combustion)
- reaction with oxygen in the air to form ethanoic acid (microbial oxidation)
- heating with potassium dichromate (VI) in dilute sulfuric acid to form ethanoic acid
Word equation for oxidation of ethanol to form ethanoic acid as a result of microbial action.
Ethanol + Oxygen -> ethanoic acid
Colour of potassium dichromate solution before + after heating
Orange
Green
Observations of oxidation of ethanol with potassium dichromate
Product smells like vinegar
Word equation of ethanol being oxidised with potassium dichromate
Ethanol + oxygen -> ethanoic acid + water
Ethanoic acid formula
CH3COOH
Give 2 ways to manufacture ethanol
- reacting ethene with steam
- fermentation of glucose
Conditions needed for reaction of ethene with steam
- 300 C
- 60-70 atm pressure
- phosphoric acid
Fermentation of glucose word equation
Glucose -> ethanol + CO2
Conditions needed for fermentation of glucose
Sugar in water, yeast, temperature of 30-40C, absence of air
Why must there be an absence of air for fermentation of glucose to occur
Otherwise the ethanol will oxidise and become sour
Why must temperature be 30-40C for fermentation of yeast?
Yeast is a living organism and its optimum temperature for fermentation is 35C. At higher temperatures the reaction nearly stops as the enzyme is denatured.
Difference between fermentation and hydration of ethene in terms of the type of process.
Fermentation - inefficient batch process where everything is put into a container and left until fermentation is complete.
Hydration- an efficient continuous flow process.
Difference between fermentation and hydration of ethene in terms of the rate of reaction.
Fermentation - very slow
Hydration- very rapid
Difference between fermentation and hydration of ethene in terms of the quality of product.
Fermentation- produces very impure ethanol which needs further processing
Hydration- produces much purer ethanol
Difference between fermentation and hydration of ethene in terms of the reaction conditions.
Fermentation- uses gentle temperatures and atmospheric pressure
Hydration- uses high temperatures and pressures, needing a lot of energy input
Difference between fermentation and hydration of ethene in terms of the use of resources.
Fermentation- uses renewable resources based on plant material
Hydration- uses finite resources based on crude oil.
Method to make an ester
- 1cm ethanoic acid + 2cm ethanol + 2 drops of concentrated sulphuric acid (acting as catalyst)
- hot water bath 5 mins
- 20 cm3 sodium carbonate in beaker then pour solution in it (this will neutralise any remaining acid)
Definition of a weak acid
An acid that forms a small number of hydrogen ions when it dissolves in water. Weak acids only partially dissociate into ions.
Are carboxylic acids strong or weak acids?
Weak
What is vinegar
An aqueous solution containing ethanoic acid
